Metal-drill.



PATENTB-D we. 1, 1905-.

0.GRAN-BERG. METAL DRILL.

PATENT orrion.

OLE GRANBERG, OF BLAIR, WISCONSIN.

METAL-DRILL.

Specification of Letters Patent.

Patented Aug. 1, 1905.

Application filed September 30, 1904:. Serial No. 226,709.

To all whom it may concern.-

to render unnecessary the removal of all of the metal in order to drilla complete hole; to prevent the drill from setting or locking, whichfrequently happens when the drill-point pierces the metal and oftenresults in the twisting or breaking of the drill; to render it possibleto drill a hole with practically a flat bottom, and generally to improveand simplify the construction of the entering end of a drill.

With the above and other objects in view, as will appear as the natureof the invention is better understood,'the same consists'in the novelconstruction of a drill, as will be hereinafter fully described andclaimed.

In the accompanying drawings, forming a part of this specification, andin which like characters of reference indicate corresponding parts,there are illustrated two forms of embodiment of the invention, eachcapable of carrying the same into practical operation, it

being understood that changes may be resorted to without departing fromthe spirit thereof.

In the drawings, Figure 1 is a View in elevation of a drill constructedin accordance with the present invention. Fig. 2 is a view looking atthe entering end of the drill. Fig. 3 is a view in transversesection,taken on the line 3 3, Fig. 1, and looking in the direction ofthe arrow thereon. Fig. 4 is a detail view in elevation, taken at rightangles to Fig. 1. Fig. 5 is a vertical sectional view showing the mannerin which the drill enters. Fig. 6 is a similar view taken at rightangles to Fig. 5. Fig. 7 is a sectional detail view showing aslightly-modified form of drill.

Referring to the drawings, ldesignates the drill, which is of the samediameter throughout its length and is provided in this instance with acylindrical head 2, to be engaged by a chuck or drill-stock, although,if preferred, it may terminate in a square end to engage a bit-stock,and as this latter construction is common and forms no part of thepresent in- VGltlOn detailed illustration thereof is omitte The drill isprovided on opposite sides with approximately V-shaped chip-grooves 3and 3'. As herein shown, the grooves are straight; but it is to beunderstood that they may be slightly twisted and still be Within thescope of the invention.

The gist of the present invention resides in themanner in which theentering end of the drill is constructed to facilitate cutting and toreduce the pressure requisite to cause drilling to a minimum. As is wellknown, in the ordinary form of drills the entering end is pointed orcone-shaped, and owing to the fact that the center of the drill has theleast speed a great pressure is required, especially with large drills,to cause it to enter the work. In the present invention theentering-point is dispensed with and the terminals 4 of the cutting-lips5 are caused to enter the work, and as these terminals are disposed atthe periphery of the drill-shank, and thus at the point of highestspeed, it will be seen that the cutting of the work will be facilitatedand that the pressure requisite to cause the drill to enter the workwill be reduced to a minimum. The cutting-lips 5 are herein shown asdisposed upon curved lines; but it is to be understood that they may bemade on straight lines and still be within the scope of the invention.

As above stated, it is an object of the invention to avoid cutting allof the metal away in order to complete a hole or opening in a piece ofwork, and as will be seen by reference to Figs. 5 and 6, by having. thecuttinglips diverge from the center of the drill outward and onoppositely-inclined angles there will be a cone portion 0 left in thework W when the drilling is completed, thereby effecting a saving in thetime that would be required to cut away this cone portion. workmen know,with the ordinary form of twist-drills unless the angles of theenteringpoint be exact when the drill punctures the metal it willfrequently lock or set, and unless great care be observed the drill willbe broken. This is due to the fact that the thin wall left in the work,which gradually increases from the point of the drill outward, yieldsand causes the lip to take a bigger bite than it can on t, and the abovetrouble ensues. With the present invention the cutting is completed atthe periphery of the drill, and if the terminals of the cutting-lips bein exact alinement As all will puncture the work simultaneously, and byreason of the pressure exerted upon the cone the latter will be forcedaway from the drill as soon as severed.

Another feature of ad vantage present in the drill of this invention isthat the same care is not required in sharpening it as with an ordinarytwist-drill, and, further, it may be used more roughly, and greaterpressure may be applied to it without danger of breakage than with thetwist-drills ordinarily in use or other drills having cone-shaped orangular entering-points.

To adapt the drill for cutting holes with approximately flat bottoms,and which is a desideratum, especially when the hole is to be internallythreaded, the form of drill shown in Fig. 7 will be employed, the onlydiiference between this and the form shown in Figs. 1 to 6 being thatthe angle of divergence of the cutting-lips 6 is reduced. This will bethoroughly effective for the purpose designed, and the change of pitchof the cutting-lip will merely cause the drill to cut slower.

Having thus described the invention, what is claimed is 1. A drill ofthe same diameter throughout, and having cutting-lips that diverge oncurved lines from the center of the drill to its periphery, theterminals of the cutting-lips constituting entering-points and formingsharp angles in conjunction with the sides of the drill.

2. A drill having one end provided with an approximately V-shaped recessand having chip-grooves on its opposite sides and intersecting the apexof the recess, the walls of the recess forming cutting-lips that aredisposed on curved lines and terminate in enteringpoints at theperiphery of the drill and on diagonally opposite corners thereof.

In testimony that I claim the foregoing as my own I. have heretoal'lixed my signature in the presence of two witnesses.

\Vitnesses:

H. Tlnonnonnnn, I-IANNAn Tlennmn.

